Besiedlungsdynamik in Primärsukzessionsflächen : Wirbellosen-Fauna im Gletschervorfeld Morteratsch

Gletschervorfelder sind eisfreie Flächen, die durch den Rückzug der Gletscher seit Mitte des 19. Jahrhunderts frei gegeben worden sind. Sie nehmen in der Schweiz bereits heute eine grössere Fläche ein als der ganze Kanton Obwalden. Erstaunlicherweise bestehen, im Gegensatz zur gut untersuchten Vegetation, bisher erst sehr vage Kenntnisse zur Fauna von Gletschervorfeldern und vielen anderen neu entstandenen Flächen. Das Forschungsprojekt «Klimawandel und Wirbellosenfauna», finanziert durch verschiedene private Stiftungen, soll hierzu etwas Licht ins Dunkel ringen. Am Morteratsch-Gletscher befindet sich eines der Untersuchungsgebiete

Lichtblick für Zürcher Wälder

Der «Aktionsplan Lichte Wälder» des Kantons Zürich sieht vor, bis 2025 auf 1000 Hektaren dauerhaft lichten Wald zu erhalten oder neu zu schaffen. Davon sollen lichtbedürftige Tier- und Pflanzenarten profitieren. Die Forschungsgruppe Umweltplanung begleitet das Projekt seit 2008. Die Resultate sind höchst ermutigend: Der Nachweis von bisher 44 tagaktiven Schmetterlingen, darunter seltene Spezialisten, spricht für sich

Schwarzgefleckter Ameisenbläuling Phengaris (Maculinea) arion (Linnaeus, 1758) (Lepidoptera: Lycaenidae) : Wiederfund im Kanton Zürich nach über 50 Jahren

Mehr als 50 Jahre nach dem letzten bestätigten Fund konnten wir den Schwarzgefleckten Ameisenbläuling Phengaris (Maculinea) arion (Linnaeus, 1758) im Juli 2016 erstmals wieder im Kanton Zürich nachweisen. Ein Männchen fand sich auf einer südostexponierten, relativ steilen Extensivweide unterhalb des Schnebelhorns (ZH, Fischenthal) auf 1150 m ü. M. Möglicherweise besteht dort eine kleine autochthone Population. Es kann aber nicht ausgeschlossen werden, dass das gefundene Exemplar per Wind aus der nächstgelegenen (vermutlich aktuell noch vorhandenen) Population rund 15 km südöstlich des Schnebelhorns verfrachtet wurde. Confirmation of Phengaris (Maculinea) arion (Linnaeus, 1758) in the canton of Zurich more than 50 years after the last verified observation. In July 2016, a male individual of the Large Blue was found on an extensively grazed, southeast-exposed, rather steep pasture below the Schnebelhorn (ZH, Fischenthal) at 1150 m a. s. l. Evidence suggests that there might be a small autochthonous local population but it cannot be excluded that the individual found was windblown from the nearest (probably still existing) population about 15 km southeast of the Schnebelhorn

Environmental gradients and succession patterns of carabid beetles (Coleoptera: Carabidae) in an Alpine glacier retreat zone

Accelerated by global warming, retreating glaciers leave behind spatially ordered moraines with underlying primary succession and disturbance. Current knowledge of primary succession comes mainly from studies of vegetation dynamics. Information about above-ground macroinvertebrates is still scarce. We used carabid beetles (Coleoptera; Carabidae) as indicator taxon to assess the effects of (1) terrain age (species turnover along the proglacial chronosequence) and (2) small-scale habitat architecture (vegetation cover, surface texture) on the carabid assembly. For this purpose, 33 sampling sites with pitfall traps were installed throughout the glacier foreland Morteratsch (Engadine, Switzerland), adjacent sparse forests serving as reference sites. With a total of 33 carabid species on the foreland and another 2 on the reference sites, the study area yielded a very high carabid species diversity compared to other glacier forelands. In general, the age of deglaciation proved to be a highly significant predictor for the carabid distribution, especially for particularly discriminant species. Observed species richness and activity densities showed bimodal patterns with a steep increase within the first ca. 40years, a decline between around 40-90years, and a further increase towards the terminal moraine. There was no evidence of dispersal-stochasticity: distinct clusters of sites with similar species composition were found. Microhabitat suitability proved to be a secondary effect, embedded in a temporal framework of primary succession. Surface cover with litter, herbs and dwarf-shrubs turned out to be the crucial habitat factors. Habitat loss as a result of climate warming will primarily affect cold-stenotopic carabids, but may potentially be absorbed by active selection for cooler microhabitat

Lebensraum Waffenplatz : Wiederfund der Gefleckten Keulenschrecke Myrmeleotettix maculatus (Thunberg, 1815) (Orthoptera: Acrididae) im Talraum der Ostschweiz nach über 80 Jahren

Erstmals seit über 80 Jahren gelang es am 17. Juli 2016, die Gefleckte Keulenschrecke Myrmeleotettix maculatus (Thunberg, 1815) im Talraum der Ostschweiz wieder nachzuweisen. Auf dem Waffenplatz Chur hat sich in einem für die Öffentlichkeit unzugänglichen Abschnitt eine Population dieser stark gefährdeten Heuschreckenart halten können. Detailuntersuchungen im Jahr 2017 an 34 Standorten mit M. maculatus-Vorkommen ergaben, dass auf dem Waffenplatz überwiegend Standorte mit spärlicher Vegetation besiedelt werden, auf denen der Deckungsgrad der Krautvegetation und der Moose /Flechten jeweils rund einen Drittel beträgt. Die bestehende Schafbeweidung wird an sich als adäquate Nutzungsform betrachtet, sollte aber künftig in geringerer Intensität erfolgen. Dies gilt insbesondere für die Trockenwiesen und -weiden von nationaler Bedeutung und deren unmittelbares Umfeld, da dort die Hauptvorkommen von M. maculatus liegen.Rediscovery of Myrmeleotettix maculatus (Thunberg, 1815) (Orthoptera: Acrididae) in the valley zone of eastern Switzerland after more than 80 years. On 17 July 2016, for the first time in more than 80 years, Myrmeleotettix maculatus (Thunberg, 1815) was detected in the valley zone of eastern Switzerland. A population of this highly endangered grasshopper species has survived in a section of the military training area Chur, which is inaccessible to the public. Detailed investigations in 2017 at 34 locations with M. maculatus occurrences showed that most of the sites had a sparse coverage; herbaceous vegetation and moss / lichens each accounted for about one third of the coverage. Existing sheep grazing is considered to be adequate, but should be less intensive in the future. This applies in particular to a subzone of protected dry grassland («Trockenwiese und -weide von nationaler Bedeutung») and its immediate surroundings with the main occurrence of M. maculatus

Environmental gradients and succession patterns of carabid beetles (Coleoptera: Carabidae) in an alpine glacier retreat zone

Erworben im Rahmen der Schweizer Nationallizenzen (http://www.nationallizenzen.ch)Accelerated by global warming, retreating glaciers leave behind spatially ordered moraines with underlying primary succession and disturbance. Current knowledge of primary succession comes mainly from studies of vegetation dynamics. Information about above-ground macroinvertebrates is still scarce. We used carabid beetles (Coleoptera; Carabidae) as indicator taxon to assess the effects of (1) terrain age (species turnover along the proglacial chronosequence) and (2) small-scale habitat architecture(vegetation cover, surface texture) on the carabid assembly. For this purpose, 33 sampling sites with pitfall traps were installed throughout the glacier foreland Morteratsch (Engadine, Switzerland), adjacent sparse forests serving as reference sites. With a total of 33 carabid species on the foreland and another 2 on the reference sites, the study area yielded a very high carabid species diversity compared to other glacier forelands. In general, the age of deglaciation proved to be a highly significant predictor for the carabid distribution, especially for particularly discriminant species. Observed species richness and activity densities showed bimodal patterns with a steep increase within the first ca. 40 years, a decline between around 40-90 years, and a further increase towards the terminal moraine. There was no evidence of dispersal-stochasticity: distinct clusters of sites with similar species composition were found. Microhabitat suitability proved to be a secondary effect, embedded in a temporal framework of primary succession. Surface cover with litter, herbs and dwarf-shrubs turned out to be the crucial habitat factors. Habitat loss as a result of climate warming will primarily affect cold-stenotopic carabids, but may potentially be absorbed by active selection for cooler microhabitats.

Erstnachweis von Brenthis daphne (Denis & Schiffermüller, 1775) im Kanton Zürich (Lepidoptera: Nymphalidae)

Der Brombeer-Perlmutterfalter Brenthis daphne (Denis & Schiffermüller, 1775) wurde im Juli 2017 erstmals im Kanton Zürich nachgewiesen. Ein einzelnes Individuum fand sich am Rand einer Waldlichtung in der Gemeinde Ottenbach (ZH). Der Fund bestätigt die kontinuierliche Ausbreitung dieser wärmeliebenden Art in Richtung Osten

Butterflies benefit from forest edge improvements in Western European lowland forests, irrespective of adjacent meadows’ use intensity

The joint effect of forest edge (FE) heterogeneity and management intensity of the adjacent farmland on FE insect communities is still poorly understood. In this study, a pairwise design was established, consisting of 36 Western European lowland FEs, with each of the 18 FE pairs containing one improved and one nearby non-improved FE. Half of the FE pairs were situated along extensively used and half along intensively used meadows, leading to gradual contrast patterns. Butterflies were selected as the survey group because they contain widely recognized flagship species and are meaningful indicators of landscape quality and resource availability. The main outcomes were as follows: (i) FE improvements led to higher overall FE heterogeneity scores, calculated on the basis of 16 floristic and structural indicator values. (ii) Overall butterfly species richness and butterfly abundance both benefited from higher FE heterogeneity. (iii) Butterfly species richness was higher on improved FEs, irrespective of adjacent meadows’ use intensity. (iv) Butterfly abundance was higher on improved FEs, mainly due to high contrast situations between improved FEs and adjacent intensively used meadows. (v) FE improvements resulted in higher butterfly indicator species richness and abundance. The strategy of the canton of Aargau in Switzerland, where this study was conducted, to ecologically improve around 200 km of additional FEs in the longer term is believed to further promote butterfly diversity in the transition zone between closed forest and open landscape

Selection of oviposition sites by libelloides coccajus (Denis & Schiffermüller, 1775) (Neuroptera: Ascalaphidae), north of the Alps : implications for nature conservation

The survival of peripheral populations is often threatened, especially in a changing environment. Furthermore, such populations frequently show adaptations to local conditions which, in turn, may enhance the ability of a species to adapt to changing environmental conditions. In conservation biology, peripheral populations are therefore of particular interest. In northern Switzerland and southern Germany, Libelloides coccajus is an example of such a peripheral species. Assuming that suitable oviposition sites are crucial to its long-term survival, we compared oviposition sites and adjacent control plots with regard to structure and composition of the vegetation. Vegetation structure at and around oviposition sites seems to follow fairly stringent rules leading to at least two benefits for the egg clutches: (i) reduced risk of contact with adjacent plants, avoiding delayed drying after rainfall or morning dew and (ii) reduced shading and therefore higher temperatures. Furthermore, the study showed that it is possible to successfully create secondary habitats for L. coccajus, as shown by a road verge in one of our study areas. It is likely that other artificial habitats such as abandoned gravel pits and quarries may also provide suitable habitats